The present invention relates to a lockable latch handle for use in connection with windows and doors for the control of opening and closing thereof.
One type of popular latch handle employs a lever attached to and rotating about the axis of a shaft generally normal to the lever. The shaft is usually connected to a latch mechanism which controls the opening and closing of a door or window.
One type of popular locking arrangement with lever-type latch handles is a barrel-type lock concentric with the shaft which is controllable by a key. Such a latch handle arrangement has a number of disadvantages. The availability of the lever extending normal to the shaft provides a means for an unauthorized user to apply considerable force and/or torque to the shaft using the lever as a means of grasping or permitting the application of tools to break the locking mechanism. For example, it is well known to slip a pipe over the end of a latch lever to obtain great leverage and thereby to apply so much torque about the shaft that the locking mechanism concentric with the shaft is destroyed. Alternatively a pry bar may be inserted under the lever and apply great force in the outward direction on the lever to draw the shaft out of the door or window.
Any of these methods of opening the latch permits the use of the controlled door or window for entry, egress or the transferring of objects therethrough.